Synthesis of (+)- and (-)-tetrabenazine from the resolution of -dihydrotetrabenazine

Tetrabenazine (1) was reduced with NaBH4 to ?-dihydrotetrabenazine (2) and then resolved with di-p-toluoyl-L-tartrate and di-p-toluoyl-D-tartrate to subsequently give (+)- and (?)-?-dihydrotetrabenazine. The enantiomers were oxidized under Swern conditions to prepare samples of (+)-tetrabenazine and (?)-tetrabenazine. The samples were optically pure by chiral HPLC analysis.